Koralm Tunnel

The Koralm Tunnel is Austria’s longest railway tunnel, stretching 32.9 kilometres beneath the Koralpe mountain range. It forms part of the 130-kilometre Koralm Railway, which connects Graz and Klagenfurt. Two parallel tunnels carry single tracks and are linked every 500 metres. The route reaches depths of up to 1,250 metres below ground. Construction involved over 800 workers and three tunnel boring machines. Six million cubic metres of rock were removed, much of it reused for noise barriers and embankments. The tunnel shortens the journey between Vienna and Klagenfurt via Graz by more than an hour. It is expected to improve rail freight links between Adriatic and Baltic ports. Local leaders in Styria argued it would boost the region’s economy and address gaps in railway infrastructure. Planning began in 1995, with environmental and geological studies carried out before construction. Over 130 exploratory wells were drilled to assess the ground conditions. Visitors cannot enter the tunnel itself, but the surrounding Koralpe offers walking trails and scenic viewpoints. The landscape above is marked by the tunnel’s route, with signs of its construction visible in places. Inside, safety features include cross-passages every 500 metres and an emergency station near the midpoint. The tunnel’s completion marks a major step in modernising Austria’s southern rail network.